1. Field of the Invention
This invention relates generally to fluid circulation systems and, more particularly, to systems for maintaining a predetermined fluid level in a fluid sump.
2. Description of the Prior Art
A typical fluid circulation system associated with a mechanism requiring a supply of fluid under pressure includes a pump for supplying the pressurized fluid, a sump containing a relatively large volume of fluid from which the pump draws its supply, a regulator for controlling the pressure of the supplied fluid, and an overage passage which returns overage fluid from the regulator to the sump. In such a system it is often desirable to maintain the fluid level in the sump within predetermined limits and, since the fluid requirements of the apparatus may vary with time, the task of maintaining fluid level becomes one of supplying fluid to the circulation system when the sump level is too low and diverting fluid from the circulation system when the sump level is too high. Many fluid level maintenance systems have been proposed, the most pertinent to this invention being those employing a remote reservoir above the sump which drains by gravity when the sump level is too low and is filled by fluid pumped from the sump when the sump level is too high. Such systems, while functional, require relatively expensive valve mechanisms because they fill the reservoir from a relatively high pressure source or, alternatively, involve electrical sensing and actuating components such as sensors and solenoid valves which, again, generate expense. A sump level maintenance system according to this invention represents an advance over these and other heretofore known systems through a new combination of simple and economical components to achieve the sump level maintenance objective.